1. Field of the Invention
The present invention relates to a detecting obstacle method and apparatus using the same, especially to a signal-transmitting and multi-receiving method of detecting obstacle and parking sensor apparatus using the same.
2. Description of Related Art
A vehicle has a rear parking sensor apparatus to detect an obstacle behind the vehicle and determine a distance from the sensor to the obstacle with ultrasonic sound when backing a vehicle. The parking sensor apparatus operates on principles similar to radar but operates at ultrasonic frequencies rather than radio frequencies. The parking sensor apparatus outputs an ultrasonic detecting signal to detect whether any obstacle is behind the rear of the vehicle and a transmitting route of the ultrasonic detecting signal is like a horn sharp.
In general, the parking sensor apparatus is attached to the rear of the vehicle and has a controller and two ultrasonic sensors. When the parking sensor apparatus is turned on, the controller controls one of them to transmit a first ultrasonic detecting signal and then waits to receive the first ultrasonic detecting signal reflected by an obstacle through the present operative ultrasonic sensor until a preset period is ended. Then the controller controls to the other ultrasonic sensor to transmit a second ultrasonic detecting signal and then waits to receive the second ultrasonic detecting signal reflected through the present operative ultrasonic sensor.
Based on the foregoing description, the controller alternatively controls two ultrasonic sensors to detect whether any obstacle exists behind the rear of the vehicle since the parking sensor apparatus uses a time division detecting method. The time division detecting method prevents all ultrasonic sensors from interfering with multiple reflected detecting signal, that are output from the all ultrasonic sensors at the same time.
However, when the time division detecting method is used to another parking sensor apparatus having at least four ultrasonic sensors, the parking sensor apparatus may require more time to determine the obstacle, that is existed behind the vehicle.
For example, if the controller needs t=60 ms to complete one transmitting and receiving procedure for each ultrasonic sensor, a driving period for each ultrasonic sensor is about 4t=4×60=240 ms. When one obstacle suddenly exits in a second detecting area of the second ultrasonic sensor and the second transmitting and receiving procedure is just ended, the obstacle is detected after 240 ms. That is, if the speed of the vehicle is 20 km/hr to back along a straight line, the obstacle is detected after the vehicle has to back 1.3 m since the obstacle exists in the second detecting area. Therefore, when the parking sensor apparatus having at least four ultrasonic sensors uses the time division detecting method, the parking sensor apparatus may require more time to determine the obstacle.